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6* Doom to R2 or max out 5* Doom

Comments
I got my 5* first, had a gem and took him up same day - super happy. Next week, I got the 6* and took him to r2 but was kind of bummed since I just ranked the 5*. If I had the 6* first, probably would have r5d someone else just for extra utility in the roster. Don't get me wrong, love both of them and variant 5 is gonna be cake with exploring now.
Either way, you're in great shape. Having double Doom is the kind of problem I don't mind at all.
I left my 5* @ r1 and don't regret it.
The only case to go with r5 sig200 first is if prestige matters to you for AQ. Otherwise, go with the 6* first